February 2008 Issue

A summary of this month's contents.

Low cost intercooler water spray controller — a sophisticated controller for turbocharged cars, this simple electronic circuit operates a water "mister" or sprayer that sprays a cooling mist onto the intercooler matrix. This lowers the intercooler's temperature and improves performance, especially on hotter days of the year.

Based on our Smart Mixture Display (Sept. 2006) circuit, only a handful of extra components are needed to produce this temperature -sensitive switch that has an LED bargraph showing intercooler temperature. A water spray pump can be adapted either from a windscreen washer pump and garden irrigation nozzle, or a solenoid pump used in domestic coffee makers.

Midi Drum Kit (Part 3): Building the sensors and stand — describing how to make both piezo-based and optically-based transducers for our Midi drum kit. You can use piezo-pad types for percussion-style input, or an optical sensor can be tapped by hand (e.g. bongo style) or for foot-activated devices.

Our article describes with full diagrams and photographs how to make a set of bongo drums, a foot controller and building a playing stand. Final part is in March 2008 which covers the software and how to drive it.

Studio Series - Stereo Preamplifier

This easy to build hifi preamp features high performance audio op.amps for ultra low noise and distortion. Its modular design incorporates five switched RCA phono sockets and support for a headphone amplifier. Full specifications, design considerations and constructional details are included in the two-part article.

Freq Response flat from 10Hz - 20kHz, -1dB @ 82kHz

Maximum input 2.9V r.m.s.

90k input impedance, 100ohm output impedance

S-N -102dB unweighted.

Correction (Page 20) The Parts List on Page 27, the value of the X2 type suppression capacitor should be 1nF 250V a.c. The power supply circuit (Fig 4) is correct.

Electrosmog Detector - a simple to build circuit will give a comparative reading of most EMFs (electromagnetic fields) that are generated by a wide range of electronic devices that surround us. Cellphones, computers, microwave ovens, fluorescent lighting and electrical power lines can all produce an 'electrosmog' that some individuals are known to be highly sensitive to.

The device was designed to detect EMFs in the region of 0 to 10 mG (milliGauss). Utilising just a few readily available components, this detector will be a fascinating project to build and use.

Also in this issue:

Teach-In 2008 - Using PIC Microcontrollers (4)

PIC n MIX — using "static" LCDs with PIC microcontrollers

Circuit Surgery concluding our discussion of SPICE simulation

Colossus and Pico - the world's first programmable electronic computer is reborn, helped along by the intervention of a modern Pico Technology ADC.